Disc Enclosure, Light Doctor, 8 Hole Light Niche
Disc Enclosure, Light Doctor, 8 Hole Light Niche
Low stock: 9 left
Ships from: Idaho Falls, ID | Memphis, TN | Tucson, AZ
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Warranty
This product includes a 12 Months manufacturer warranty.
Product Information
Description
Light Doctor 8-Hole Niche Disc Enclosure
Cap the niche. Stop the leak.
The Frank Wall Enterprises Light Doctor TLD8D (PST-57-256-1055) is an 8-hole Lexan® disc enclosure that permanently seals a damaged or retired pool light niche on vinyl liner pools. It bolts to an 8-hole bolt pattern with 10-1/2" hole-to-opposite-hole spacing and installs in front of or behind the liner. It cross-references OEM parts 3503-009 and 905359, so you can drop it in without re-engineering the wall.
Built to Outlast the Pool
You get a single piece of Lexan® polycarbonate instead of a stacked gasket repair. Lexan shrugs off chlorine, salt, UV, and the freeze-thaw cycle that finally killed the original niche, so the wall stays sealed long after the failed fixture is gone. Backed by a 12-month manufacturer warranty, this is the part that ends the leak instead of postponing it.
Drop-In 8-Hole Fit
Use a tape measure on the existing niche before you order. Hole to opposite hole should read 10-1/2" and adjacent holes should sit 4" apart on an 8-hole pattern. If you already have OEM 3503-009 or 905359 on the parts tag, this disc is the direct replacement and bolts onto the original screw holes with zero re-drilling.
Install Front or Behind the Liner
Mount the disc in front of the liner when you want a serviceable, revisitable repair, or sandwich it behind the liner during a liner replacement for a clean wall with no visible hardware. Either path seals the original 8-hole pattern against the niche flange, which lets you decide between cosmetics and serviceability instead of being forced into one approach.
Who It's For
Vinyl Liner Pools
Engineered for vinyl liner walls, where a failing 8-hole light niche threatens both the liner and the wall behind it.
Damaged Niche Repair
Replace a cracked, leaking, or corroded 8-hole light niche with a single sealed disc instead of cutting the wall open.
Retired Light Niches
Going from a wet-niche fixture to perimeter LEDs or a floating light? Permanently cap the old niche without re-plumbing the wall.
OEM Cross-Replacement
Direct drop-in for OEM parts 3503-009 and 905359, both common 8-hole niche discs on older vinyl liner builds.
Why PST Customers Pick This
Stops Niche Leaks
Replaces a failed light housing or gasket stack with one sealed disc, so water stays in the pool instead of behind the liner.
Original Bolt Pattern
Uses the existing 8 mounting holes, no drilling, no enlarged openings, no permanent damage to the niche flange.
Lexan® Hardness
Polycarbonate stands up to chlorine, salt, and pH swings far better than ABS or acrylic discs sold for the same job.
Verified by Measurement
Published 10-1/2" and 4" hole dimensions let you confirm fit before ordering, no guessing on legacy niches.
Liner-Friendly
Smooth disc face sits flush against the liner, with no sharp edges that snag, crease, or stress the vinyl over time.
Frank Wall Quality
Built by Frank Wall Enterprises, the brand pool techs use when they want a niche problem to stay fixed.
Installation Notice
This disc seals a wet-niche penetration in your pool wall. A poor seal can drive water behind the liner and rot the wall structure. If the original light circuit is still live, kill the breaker and verify zero voltage at the niche before you touch it. If you are not comfortable bonding the niche per NEC Article 680 and inspecting the liner attachment, hire a licensed pool service technician.
Full Specifications
Frequently Asked Questions
What is the difference between the 6-hole, 8-hole, and 10-hole Light Doctor discs?
The number refers to the bolt pattern on your existing light niche, not the disc itself. Count the screws around your niche or the empty bolt holes if the fixture is already out. If you count 8 holes spaced about 4" apart with 10-1/2" from a hole to the hole directly across, this TLD8D 8-hole disc is the right part. Wrong hole count means a different disc, so verify before ordering.
Does this replace OEM parts 3503-009 or 905359?
Yes. The TLD8D is a direct drop-in for both 3503-009 and 905359, two of the most common 8-hole light niche discs found on older vinyl liner pools. Match the bolt pattern, confirm the 10-1/2" and 4" measurements, and the disc bolts onto the existing screw holes.
Will this work on a concrete or fiberglass pool?
No. The TLD8D is engineered for vinyl liner pools only. Concrete, gunite, and fiberglass niches use different sealing methods and require purpose-built closure rings or a replacement fixture.
Can I install this myself?
Many vinyl liner owners install the TLD8D themselves with the pool partially drained below the niche. Kill the original light circuit at the breaker, remove the failed fixture, clean the niche flange, then bolt the disc to the existing 8-hole pattern with stainless niche screws. If you are not comfortable working at a wet niche or interpreting bonding requirements under NEC Article 680, have a licensed pool technician do the install.
Do I install it in front of the liner or behind it?
Both are correct, you choose. Mounting in front of the liner is faster and fully serviceable, which works well if you may revisit the niche later. Mounting behind the liner hides the hardware for a cleaner wall, but is usually done during a liner replacement when you have access to the flange before the new liner goes in.
Does it include screws or a gasket?
The TLD8D ships as the Lexan® disc only. Most installers reuse the existing niche fasteners and add a fresh bead of pool-rated silicone or butyl sealant at the disc-to-niche contact face. If the original screws are corroded, replace them with new stainless niche screws before installing the disc.
If I install this, can I still add lighting later?
Yes, but not at this niche, since the disc is intended as a permanent enclosure. Most customers pair the TLD8D with surface-mount perimeter LEDs, floating pool lights, or a new flush LED puck installed in a different wall location.
Order the TLD8D From PST
Authorized Frank Wall Enterprises dealer. Backed by PST Pool Supplies' service team, with help on the line before and after your install.
Additional Info
| Category | Parts Pool Parts Pool Light Parts |
| SKU | PST-57-256-1055 |
| MPN | TLD8D |
| Replaces | 3503-009, 905359 |
| Manufacturer | FW Enterprises |
| Weight | 1.23 lb |
Let customers speak for us
Easy fix for small leak around valve in concrete pool.
Definitely recommend this shop!
We are running big and deep pool and we get all what we need from here
I had trouble finding the right part that would fit. PST helped me figure out exactly the right part and fit.
Helped me get my light installed correctly after liner change
This machine cleans 10 times better than my previous one and is worth the cost. However, I’ve only had it for 2 weeks. The last one lasted about 6 months and never cleaned well even though it had 4 stars when I bought it. I hope this new one remains strong for a few years
The pump was a great value and it was described perfectly. The product was shipped fairly quickly and it was well-protected
After much research the value of the product is good. It was shipped fairly quick and it arrive in a well-protected package.
Very happy with this purchase fits and work as described fast shipping
Loved how fast it got here. It has small wiring and I was glad it was in a protective envelope and it arrived without breaking.
just as listed. well packeged, fast ahip, works fine. purchased to remedy issue with heater and ozone injectorboth operating together. might have been able to just bend old switch a bit but did not try that.
Great customer service and knowledge of product. Asked of compatibility and they had the answer. My intouch2 was not working so I researched new intouch3 from Spa Dealer and they wanted $75 just to come out, then $125 for up to an hr...just to confirm what I already knew. Contacted PST and they had the product and confirmed compatibility. Saved me some $$.Thanks PST.
